For healthy blood pressure, both numbers matter

The bottom number in a blood pressure reading (the diastolic pressure) has sometimes played second fiddle to the top number (systolic) in clinical settings, but new research confirms that both numbers are important in determining a person’s heart disease risk.

The study, from researchers at Kaiser Permanente in California, was published Wednesday in the New England Journal of Medicine.

“Although systolic does count for a little bit more in terms of the risk of heart attack and stroke, diastolic high blood pressure is a close second, and it’s an independent predictor of those risks,” said lead author Dr. Alexander Flint, a stroke specialist with Kaiser Permanente.

A high diastolic number “really should not be ignored,” he added. “We should not declare victory just because one number is under control. We need to pay attention to both.”

Systolic refers to the amount of pressure in a person’s arteries, when the heart squeezes and sends blood throughout the body. Diastolic is the pressure in the arteries between heart beats.

The study analyzed more than 36 million blood pressure readings from 1.3 million adults. All were members of Kaiser Permanente in Northern California. Most were white; just 7.5 percent were black.